1. Field of the Invention
The present invention pertains to a core holder for testing the characteristics of geologic formation core samples.
2. Background
Geologic core holders have been developed of a type which permit testing the fluid flow characteristics of a geologic core sample at various temperature and pressure conditions. One deficiency of known types of core holders has been revealed as a result of the introduction of the use of computerized tomographic scanners for viewing the fluid flow patterns through various types of core samples under laboratory conditions. Metal core holders made of metals of high atomic number are particularly unsuitable in that the attentuation of the x-rays do not permit the use of these types of holders for producing computerized tomographic images. The substitution of metals of lower atomic numbers is unsuitable for many laboratory test conditions because of the pressure and temperature limitations at which metals such as aluminum may be used.
Accordingly, a profound need has been realized for the development of a geologic core sample holder which provides minimum attentuation of x-rays to permit the x-ray imaging of cores under various test conditions. There has also been a need to develop a core holder which will withstand the test pressures and temperatures needed to simulate actual subterranean formation environments and recovery processes which are likely to yield commercially viable quantities of hydrocarbons such as the West Sak and Ugnu oil fields in Alaska.
Still further, it has been recognized that the specialized use for a suitable core holder meeting the criteria mentioned above makes the cost of these structures relatively significant, and, accordingly, the need for a more versatile core holder suitable for operating under various conditions of core sample length and diameter, and core sample test conditions, has been particularly great. The need for an improved core holder has been recognized, not only in connection with the use of x-ray linear core scans and computerized tomographic scans, but magnetic measurements of core samples has also been viewed as requiring the use of non-magnetic core holders. Accordingly, the problems and desiderata associated with the development of an improved core holder have heretofore been unresolved but are largely met by the improved core holder of the present invention.